This invention relates to mineral cutter picks and pick assemblies for mineral mining, e.g. for coal cutting.
In mining operations it is often desirable to use a fluid spray close to the cutting face in order to limit the spread of dust and/or for cooling. It is of course desirable that the fluid should be directed very close to the cutting operation to be effective, and it has been proposed to direct a flow of water through a passage that extends through a cutting pick from an entry in the rear face of a shank of the pick to near its cutting tip. The water is fed from supply conduit in a cutter head in which a number of picks are held, and there are tubular elements provided for a plug-in connection for each pick as the picks are mounted on the cutter head.
Leakage from such a connection can be a problem, because it must be realised that in the difficult and dirty conditions that usually obtain in mining operations, it is difficult to provide and maintain close tolerances.
According to one aspect of the invention, there is provided a pick assembly comprising a cutter pick and holding means for said pick having an aperture in which a shank of the pick is received, passages being provided in said holding means and the pick for the supply of fluid to an opening adjacent a cutting tip of the pick, connector means between said passages of the holding means and the pick comprising a tubular element received in sealing means in such a manner as to accommodate displacement between the connected passages, said sealing means comprising a sleeve at an end region of one of said passages and having an inner face in engagement with an end of the tubular element and an outer face which is exposed to the supply pressure of said passage end region, whereby to assist sealing of the tubular element outer periphery therewith.
Preferably, the application of fluid pressure to said outer face of the sleeve is obtained by providing an annular space around the sleeve opening into the adjacent fluid passage.
Advantageously sealing sleeves are provided in the adjacent end regions of said passages in both the holding means and the pick, each with an outer face exposed to the supply fluid pressure to engage respective ends of a separate tubular connecting element. The sealing sleeves do not need to have corresponding forms, however.
Leakage from a fluid connection to a passage in a cutter pick can also occur because of movements between the pick and its holding means, for example, the conventional pick shank (other than those with fitted tapers) does not match its mounting slot exactly and in any case during use a slackness can develop. The cutter pick is then not fixed rigidly to the cutter head and the method of connection of the fluid supply to it must therefore allow for significant movement of the pick in its mounting.
According to a further aspect of the present invention, there is provided a pick assembly comprising a cutter pick and holding means for said pick having an aperture in which a shank of the pick is received, passages being provided in said holding means and the cutter pick for the supply of fluid to an opening adjacent a cutting tip of the pick, connector means between said passages of the holding means and the pick comprising a tubular element having opposite ends of larger external cross-section than an intermediate region between said ends, sealing means adjacent the ends of the passages in the tool and holding means engaging said larger ends of the tubular element in a manner permitting pivoting movements of both said ends and reciprocating movements of at least one of said ends on contacting faces of said sealing means, whereby to accommodate misalignment between the connected passages.
Preferably, said larger ends of the tubular element are part-spherical in form. It is also preferred that the sealing means engage said larger ends so as to restrain axial movement relative thereto, the sealing means for one of said passages having a lesser resistance to said axial movement for allowing reciprocatory movements when in use and during sliding engagement and disengagement of the tubular element therewith.
The invention is also directed to sealing means for use in a pick assembly as aforesaid, and to cutter picks and pick holding means provided with such sealing means.